O

The interior gi slab to close > end to the PIot Figure 16.26 Flanking around Slabs at Curtain Walls The interior gi slab to close > end to the PIot Flanking paths sometimes occur at column penetrations of slabs, particularly where the lower floor space has an open ceiling. In each of these conditions the openings around the column must be closed off with a material that has a sound transmission loss equivalent to the floor system. Moveable walls, used as dividers between meeting rooms, are...

Appliances And Other Sources Of Noise

Footfall impacts on stairways can be conducted structurally through the studs, which support the stair risers. This, in turn, is radiated by the panels attached to the wall studs. In townhouse (two-story) condominiums and apartments it is good practice to locate the stairways on the interior of the unit away from the party walls. When this is not possible the stairways should be supported separately and the risers must not be physically attached to the wall framing or drywall. The party wall...

Info

And simplifying, we obtain the sound power level at the reference end in terms of the break-in transmission loss where Lwoi sound power breaking into the duct at a given point (dB) Lwo sound power level incident on the outside of the duct (dB) ALTLoi sound transmission loss from the outside to the inside of the duct (dB) D duct loss correction term (dB) Ver (1983) has developed simple relationships between the breakout and break-in transmission loss values based on reciprocity. Above cutoff...

Exterior Curtain Walls

Interior partitions separating adjacent offices will eventually meet an exterior wall. Ideally, the interior wall should join the exterior surface at an area of solid construction, so that acoustical isolation is maintained. When the walls intersect at a window mullion or at the glazing there can be a flanking path at the junction, particularly if the window is double glazed. Exterior window mullions are constructed from thin (typically 0.090 or 2 mm), hollow, rectangular aluminum extrusions...

Figure 2114 Summary of the Results of the Nippon Gakki Listening Tests Kishinaga et al 1979

Broadening of listener position could have contributed to the overall impression. However, based on this study, the highly absorptive configurations seemed to generate the most favorable responses. Imaging in theater systems, using a left-center-right loudspeaker configuration, is less complicated than in stereo systems. Ideally the three front loudspeakers are located behind a perforated screen about 5 8 of the screen height up from the bottom. The two outside loudspeakers are placed close to...

Longitudinal Section

This arrangement freed up the center of the room for a client couch and social area instead of being dominated by a massive mixing console. The studio consists of three rooms accessed from a small foyer separating the studio from the control room. Foyers can sometimes be used as isolation rooms particularly if there is a need for feedback such as with an electric guitar. Two isolation booths, with sliding glass doors, are available for individual instruments such...

M O

Investigators use tapping machines, walking at a normal pace (about 2 steps per second), and a heel drop test, where a subject raises up on his toes and drops his full weight back on his heels, as impulsive sources. This latter test represents a nearly worst-case scenario for human induced vibration, with aerobic studios and judo dojos being the exception. After studying a number of steel-joist concrete-slab structures, Lenzen (1966) suggested that the original Reiher-Meister scale could be...

Renaissance Period 14001600

Sabbioneta Theater

The great outpouring of art, commerce, and discovery that was later described as the Renaissance or rebirth, first started in northern Italy and gradually spread to the rest of Europe. The development of new music during these years was rich and profuse. Thousands of pieces were composed and, while sacred music still dominated, secular music also thrived (Hemming, 1988). Church construction still continued to flourish in the early years of the Renaissance. St. Peter's Cathedral in Rome, the...

Wq

When this equation is written as a level by taking 10 log of both sides where Lp sound pressure level (dB re 2 x 10 Lw sound power level (dB re 10 12 W) Q directivity (dimensionless) S area of the radiating surface (m2 or ft2) z measurement distance from the surface (m or ft) K 0.1 (z in m) or 10.5 (z in ft) for standard conditions Equation 2.91 gives the sound pressure vs sound power relationship for a planar surface at all distances. When a measurement is made close to the surface, the...

Undamped Absorber

Figure 11.20 Forced Response of a Two Degree of Freedom System Near Resonance (Ruzicka, 1971) Transmissibility curve for a spring mass system to which is attached a passive vibration absorber tuned so as to suppress the main system resonant response. relevant floor area, are hung between the ceiling and the slab. It is not advisable to use the ceiling itself as the dynamic absorber, since mass damping works to minimize floor motion by maximizing the motion of the suspended mass. If the ceiling...

Figure 138 Types of Centrifugal Fans

Vane axial fans have fixed stator blades to straighten the flow after it passes through the rotor blades tube axial fans do not. Centrifugal fans consist of a series of blades, arranged at even intervals around a circle like a waterwheel, that throw the air from the inside to the outside of the circle as they rotate. Forward curved blades push the air out much like a jai alai racket. The air leaves the fan blade at a velocity higher than that of the blade tip. In backward-curved or...

O Io 2 O 3 O Ao 5 O

Pyramids, angled so that one side is parallel to the stage floor. This provides high-frequency reflections back to the musicians. In multipurpose auditoria the orchestra enclosure must be removable for theatrical performances. The shell ceiling can be designed to be flown from the rigging when there is a fly tower. If individually suspended clouds are used above the orchestra, bass energy will be lost into the absorptive fly tower and orchestral balance will suffer. Consequently a continuous...

Types Of Isolators And Bases Used In The Tables

W 3 8 THICK, 40 DUROMETER RIBBED NEOPRENE PADS WSW 3 8 THICK, 40 DUROMETER RIBBED NEOPRENE PADS SEPARATED BY A 10 GAUGE STEEL SHEET - LOADED TO 50 PSI N NEOPRENE IN SHEAR MOUNTS HAVING A 0.25 RATED DEFLECTION WITH INTEGRAL STEEL PLATES AND TAPPED HOLES FOR BOLTING EQUIPMENT ND DOUBLE DEFLECTION NEOPRENE MOUNTS HAVING A 0.4 RATED DEFLECTION WITH STEEL PLATES AND TAPPED HOLES FOR BOLTING EQUIPMENT V HOUSED STEEL SPRING AND 3 8 NEOPRENE ISOLATORS

Flow Noise in Straight Ducts

Once air has been set in motion it can generate noise by creating pressure fluctuations through turbulence, vortex shedding, mixing, and other mechanisms. Steady flow in a straight duct does not generate appreciable noise, when compared with other sources such as abrupt transitions in the air path, takeoffs, and elbows. Figure 13.16 (Fry, 1988) shows sound power Figure 13.16 Sound Power Spectra of 600 mm (24 in) x 600 mm Straight Steel Duct for Various Air Velocities (Fry, 1988)

Figure 191 Simple Plan Forms for Concert Halls in Normal and Surround Configurations

Chambers, are at or above 400 cu ft (11.3 cu m) these also feature a large moveable reflector above the orchestra which offsets some of the effects of a high volume. Heavy plaster is the most commonly encountered wall and ceiling material used in concert and opera halls. In buildings more than 100 years old it was convenient since it could be worked in a semi-liquid state and would dry to a hard surface. Backings in these old buildings

Lateral Section

A canopy built above the platform housing the loudspeakers, video screens, and lighting instruments is the best choice. Since religious services can reach levels of 95 dBA or more, the sound system is large and requires a steel structure to provide support and access to the clusters. Amplifier racks should be located close to the loudspeakers to reduce the amount of heavy-gauge wire needed to be pulled. Ample power can be made available from nearby electrical rooms. Local step-down transformers...

Arena Stase

OPEN PROSCENIUM STASE OPEN STASE that when the actors face away from the audience, their voices are reflected back toward the seating area. Rear walls in theaters and small auditoria are almost always absorptively treated. This is the case even with small recital halls, where high-reverberation times are desirable and difficult to obtain, since excessive loudness results from a hard back wall. Even if the program lists only small-group performances, eventually a small orchestra will be...

Orchestra And Balcony Floor Flans

It helps reflect sound, primarily bass, to the audience. 4. It creates a local reverberant (diffUse) environment for the musicians. 5. It forms an attractive architectural backdrop for the orchestra, consistent with the design of the remainder of the auditorium. 6. If it is modular in construction, it can be stored efficiently when not in use. Following these design goals we can attempt to find a Goldilocks solution neither too deep, too high, nor too wide just right. Depth is particularly...

Upper Balcony Plan

10 O 2O 40 feO SO Feet 5 O 10 20 30 Meters Design of Rooms for Music 695 Table 19.14 Selected Technical Data for Theatro Alla Scala (Beranek, 1996) Volume (V) Dimensions (LWH) Furthest Seat (D) Seating (N) 11,252 cu m 30.2 m x 20.1 m x 19.2 m 32 m 397,300 cu ft 99 ft x 66 ft x 63 ft 105 ft 2289 (including 154 sight restricted seats) 1,635 sq m 17,600 sq ft TE(Unocc) 1.2 s (1 - IACCE3) 0.48 horizontal above the orchestra, providing some additional support for the orchestra, though at a delay of...

Codes And Standards

In Chapt. 9 we discussed the formal procedures for the measurement of the airborne sound transmission loss and the determination of the sound transmission class (STC) of a partition. The STC is a weighted average of the transmission loss values at 16 third-octave band frequencies, which is normalized using the area of the common partition and the absorption in the receiving room. Many cities and states have adopted minimum code standards for the STC ratings in multifamily dwellings and these...

Speech Privacy In Open Offices Privacy

When the intelligibility of speech is low, not surprisingly it follows that the privacy is high. Table 16.1 (ANSI S3.5) shows the relationship between Articulation Index, signal-to-noise ratio, and privacy. Written characterizations of these degrees of privacy were given in Table. 3.6. In an office environment, where speech privacy is the goal, we can strive to achieve the required signal-to-noise ratio in several ways. The general form of the intelligibility equation is

Section

Cement board, having a surface mass density of 10 lbs sq ft (49 kg sq m) or greater, can be used on the exterior with double drywall interior surfaces supported on a separate framing system or resilient isolators. In most cases the garage door must be removed, although it can be retained as an applied decorative element over the exterior wall. A garage ceiling is too low and raising it requires added structural framing and review by a structural engineer. It should be double-drywall resiliently...

Concrete on Metal Pans

Concrete poured into a sheet metal pan supported on metal joists can deliver reasonable sound isolation if it is combined with a suspended drywall ceiling. Figure 12.1 gives several examples. The ceiling is supported from hanger wires at 4'-0 (1.2 m) on center that are tied to a 1.5 (38 mm) carrying channel (called black iron). A 7 8 (22 mm) thick hat channel is wire tied or clipped to the black iron and the gypsum board is screwed to it. STC ratings for this construction vary with the airspace...

Sn

Duct silenc-er at the roof penetration down-discharge configuration. For purposes of noise control, the side-discharge units are much preferred since this allows space for the installation of silencers in a horizontal run of duct. In down-blast units, the air and noise issue straight down out of the unit, allowing very little room for a silencer or other attenuating mechanism. Figure 15.24 shows the preferred configuration for side-discharge units with silencers installed in the vertical drop....

Floor Vibrations

The vibration of floors due to motions induced by walking or mechanical equipment can be a source of complaints in modern building structures, particularly where lightweight construction such as concrete on steel deck, steel joists, or concrete on wood joist construction is used. Usually the vibration is a transient flexural motion of the floor system in response to impact loading from human activity (Allen and Swallow, 1975), which can be walking, jumping, or continuous mechanical excitation....

Figure 1311 A Variable Air Volume Unit

Figure 13.12 Range of Discharge VAV Noise Levels at Two Operating Points Figure 13.12 Range of Discharge VAV Noise Levels at Two Operating Points Figure 13.13 Range of Radiated VAV Noise Levels at Two Operating Points (Blazier, 1981) Tests on 5 manufacturers' boxes (average + 1 standard deviation,) Figure 13.13 Range of Radiated VAV Noise Levels at Two Operating Points (Blazier, 1981) Tests on 5 manufacturers' boxes (average + 1 standard deviation,) Figure 13.14 Comparison between Published and...

DESIGN and Construction of Multifamily Dwellings

As the growing population is extruded into urbanized areas, multifamily dwellings must be constructed to accommodate the higher densities. Pressures of population and cost force people together, and noise and noise transmission between occupied spaces become significant concerns. People want their homes to be quiet and free from intrusions, like a single-family residence. The most common complaints are about noise transmission through floor-ceilings, footfall noise, and noise due to the...

Home Studios

Home studios, sometimes known as project studios, are increasingly common as high quality recording equipment becomes smaller and more affordable. The sophistication of this electronic gear has a direct influence on the proliferation of small studios since excellent recordings can now be made in a low-cost environment. The result has been a reaction from commercial studios trying to limit their number through land-use regulations. Under pressure from the commercial studios, cities such as Los...

DESIGN and Construction of Office Buildings

Commercial buildings present a set of design issues that differ somewhat from those encountered in residential structures. In critical spaces such as classrooms, theaters, and studios, much of the information presented in Chapt. 15 is still applicable. In commercial office buildings the uses can vary, and may include less sensitive spaces. Structures are likely to be multistory, with an air handling unit on each floor located in a central core, along with other services such as elevator shafts,...

Heating

Figure 13.10 Air and Heat Flow in a Heat Pump System (California Heat Pump) The shaded pipes indicate areas of high pressure. flows to the compressor, which further warms and pressurizes it by performing mechanical work on it. The hot gas then flows through a coil where a fan blows air over it and into the occupied space. The gas gives off heat in the exchange and condenses into a liquid. The liquid is then forced under pressure through the capillary tube where it expands and is returned to the...

Figure 2113 Standards for Loudspeaker Placement in Studios Listening Rooms and Theaters

Surround R Surround arrangements of absorption in a room. The test room had a hardwood floor and an absorptive ceiling, not a typical home environment. Since these data are over 20 years old, no diffusers were included in the mix of materials. The parameters used for judgment were 1. Localization of the stereo image 5. Perspective (probably quality of the soundstage) (Everest, 1994) The results are summarized in Fig. 21.14. No one arrangement of materials...

Table 36 Degrees of Acoustical Privacy Chanaud 1983

Cannot Confidential understand speech of others. May not be Privacy aware of presence of others. May not hear activity sounds of others. Confidential conversations possible. No distractions. Difficult to converse with others. Normal Occasionally hear the activity sounds of Privacy others. Aware of the presence of others. Speech and machines audible but not distracting. Confidential conversations possible only under special conditions. Complete privacy. Sense of...

Mechanical Equipment Split Systems

Mechanical systems in residential structures provide heating, ventilating, and air conditioning (HVAC) services to the building. The thermodynamic principles were discussed in Chapt. 13. A typical system consists of an external air-cooled condenser, which gives up heat to the outdoors in the process of compressing a circulating refrigerant. The refrigerant is pumped through copper pipes to a fan coil unit where it is forced through an expansion valve and a coil, where it changes state from a...

Figure 213 The Phenomenon of Beats

Beats are created when two sine waves having nearly the same frequency are combined. Beats are created when two sine waves having nearly the same frequency are combined. are encountered when two fans or pumps, nominally driven at the same rpm, are located physically close together, sometimes feeding the same duct or pipe in a building. The sound waxes and wanes in a regular pattern. If the two sources have frequencies that vary only slightly, the phenomenon can extend over periods of several...

Duct Flanking

HVAC ducts can also serve as a conduit for sound transmission between adjacent rooms, particularly if they are unlined. If an unlined duct directly connects diffusers in adjacent offices, sound can propagate along the duct and be heard clearly in the receiving room. To calculate this effect, the duct attenuation becomes the transmission loss and the cross sectional area of the duct becomes the transmitting area in Eq. 10.5. Where the supply or return air is ducted directly between sensitive...

Reflections From Finite Objects

Reflection from finite planar surfaces is of particular interest in concert hall design, where panels are frequently suspended as clouds above the orchestra. Usually these clouds are either flat or slightly convex toward the audience. A convex surface is more forgiving of imperfect alignment since the sound tends to spread out somewhat after reflecting. If a sound wave is incident on a finite panel, there are several factors that influence the scattered wave. For high frequencies impacting near...

Structural Connections

In the previous theoretical analysis, it has been assumed that there were no structural connections linking the panels, in either the double or the triple constructions. The only means of connection between the panels was through the coupling provided by the air space. In actual building construction, there are studs, joists, and other elements that provide the structural support system and physically connect panels together. These produce a parallel means of sound transmission, by way of...

T2 x2 y2 z2 2tx0x1 y0y1 z0z1 x2y2

The canonical equation of a paraboloid is (Hanrahan, 1989) Although more complicated shapes are seldom necessary in acoustical ray tracing their implicit functions can be found in computer graphics texts such as Glassner (1989) or Hill (1990). Both quadric and superquadric shapes are also addressed in Ray Tracing News (RTNews), a web site maintained by Eric Haines.

Note That The Throat Is Moved Towards The Mouth To Accommodate The Wider Coverage Ansle

This detail is emphasized in the White horn series they designed however, the idea predates this horn (Keele, 1983). The narrow throat allowed the use of a larger driver and improved the directional control by letting the sound illuminate the sides of the horn, without the high-frequency beaming usually associated with larger throat sizes. The second feature was a conical-exponential (CE) throat shape, which consisted of an exponential throat over a certain distance, after which...

Baroque Period 16001750 Baroque Churches

The first half of the seventeenth century was dominated by the Thirty Years War (16181648), which ravaged the lands of Germany and central Europe. This confusing struggle was one of shifting alliances that were formed across religious and political boundaries (Hindley, 1965). The end result was a weakening of the Hapsburg empire and the rise of France as the dominant power in Europe. Italy became a center for art and music during that period, in large part because it was relatively unscathed by...

George Izenour Theater Design Hydraulic Ceiling

Gypsum board or 1 3 8 (35 mm) plywood. These widths are feasible in fixed enclosures but difficult in a modular shell, which is constrained by weight to a maximum thickness of 5 8 (16 mm). Where thin wood is used, it can be shaped into a convex curve and backed with closely spaced structural stiffeners to reduce diaphragmatic absorption. Curves are constructed by laminating several thin sheets together. Heavy shells can be accommodated using air castors or rails. Figure 20.15 shows the...

Historical Introduction

The arts of music, drama, and public discourse have both influenced and been influenced by the acoustics and architecture of their presentation environments. It is theorized that African music and dance evolved a highly complex rhythmic character rather than the melodic line of early European music due, in part, to its being performed outdoors. Wallace Clement Sabine (1868-1919), an early pioneer in architectural acoustics, felt that the development of a tonal scale in Europe rather than in...

Figure 227 Definition of a

Parametric form, using an origin (o), a direction vector (d), and a parameter (t) denoting the distance along the direction vector. Figure 22.7 gives an example. For example the line segment between points a and b is where t is defined over the interval t e ta , tb , and in this case, t e 0, 1 . The direction vector is normalized to 1, and t can range to infinity. Equation 22.4 is an explicit or parametric form of the ray equation since any point on the ray can be determined simply by varying...

ROOMS for MUSIC

Rooms designed for unamplified music are the most visible and interesting spaces in architectural acoustics. It is here that the science of acoustics and the arts of architecture and music are blended. From the standpoint of acoustical design, the concert hall requires the most careful control, but gives the acoustician the fewest tools to accomplish the task. In contrast to sound system design, where a loudspeaker configuration can yield a very predictable result, the design of a hall for...

Figure 742 Quarter Wave Resonator

A charter wave resonator tube in an infinite baffle. where is the propagation constant. The tube has small viscous and thermal loss components and the imaginary part of the propagation constant, from an approximation originally due to Kirchoff, can be used to account for them There are two impedances to be included in the analysis one having to do with the interaction between the incoming wave and the end of the tube, which was given in Eq. 7.122 and the other having to do with the radiation of...

Table 158 Maximum Intrusive Noise Levels Due to Plumbing

Minimum Quality Medium Quality High Quality the pipes must be sized large enough that flow generated noise is kept to a minimum. Table 15.9 shows recommended pipe sizes and the maximum flow velocities and flow rates (Wilson, Ihrig & Associates, 1976). A tub fills at a rate of about 8 gal min so that a 1 (25 mm) pipe would be appropriate. A low-flow shower supplies water at about 3 gal min so a minimum 3 4 (19 mm) pipe could be used. Where multiple fixtures are served the supply pipes should...

Table 1310 Level Adjustments for the NEMA Rating of a Transformer dB Miller 1980

Octave Band Center Frequency, Hz 31 63 125 250 500 1k 2k 4k 8k CT -1 5 7 2 2 -4 -9 -14 -21 through a string tied around the unit), and the correction term, which includes the 10.5 dB adjustment for the power to pressure conversion. Table 13.10 gives the correction term for an unenclosed transformer. Lw NEMA rating + 10 log ST + CT (13.35) where Lw OCT octave band sound pressure level (dB) ST surface area of the transformer (ft2) CT octave band correction (dB) Over time, transformers can grow...

Sound Stages

Sound stages are large open rooms used for indoor movie production. Acoustically they are designed to be dead with all surfaces except the floors covered with 4 to 6 inch (100 to 150 mm) deep blankets of absorptive material. The floors are smooth and flat so that cameras can be dollied. The exposed wall surfaces can be faced with commercial quilted blankets covered with hardware cloth below an elevation of 10 ft (3 m). The best rooms are built with isolated construction, floated floors,...

Fan Coil Units and Heat Pumps

In small offices and residential installations split HVAC systems are often used. These consist of an air-cooled condenser outdoors and a fan coil indoors as illustrated in Fig. 13.2. A refrigerant is circulated between the two devices moving under pressure in mostly liquid form between the condenser and the fan coil, and returning as a gas. The high-pressure liquid is forced through an expansion valve and thence into a cooling coil, where heat is removed from the room air. The main source of...

Figure 1510 Steel Deck and Concrete Floor Ceiling Constructions

5 025 mm Thic-k Lightweight Concret on Metal Decking R-11 Batt (3.5 or tQ mm) Insulation 5 6 (Ife mmj Sypsum Board on Hat Channel 5 025 mmj Thick Lightweight Concrete on Metal Decking R-11 Batt (3.5 or IQ mm Insulation Q.I5 DeFiection Neoprene Isolators 5 6 (Ife mm) Sypsum Board on Hat Channel and Carrying nannel 5 025 mm Thick Lightweight Concrete on Metal Decking R-11 Batt (35 or 1 mm Insulation I (25 mm DeFiection Spring Isolators 5 6 fife mm Supsum Board on Hat Channel and Carrying Channel...

General Design Parameters

The ideal listening environment for live music depends to some degree on the type of music being played. There are, however, a number of common elements about which there is general agreement. 1. The audience should feel enveloped or surrounded by the sound. This requires strong lateral reflections with a significant fraction of the energy arriving from the side. 2. The room should support instrumental sound by providing a reverberant field, whose duration depends on the type of music being...

Rooms For Mixing Dubbing Stages

Dubbing stages are large screening rooms, about the size of a commercial movie theater, with a full-sized projection screen and a single floor of opera chair seating. In the center of the seating is an area for three sound mixing consoles, one each for dialog, music, and effects, arrayed in a line across the theater. The film is projected on the screen using a projector fed by dubbers, which historically were mechanical transports that could be played forward or backward in synchronization with...

Figure 218 Configurations that Generate Flutter Echo Reverberation

Revebration Time Room Volume

Everest (1994) divides the reaction to a reflection into four regions according to the time delay. Region 1, where directional cues are determined, is less than 1 ms Region 2 is up to about 50 ms, where the integrating effects of the ear occur Region 3 is an intermediate zone, which depends mostly on reverberation time, and Region 4 is that of a long-delayed reflection where the curves in Fig. 21.6 flatten out and approach the horizontal. Clark (1983) performed an interesting series of studies...

Party Wall Construction

In actual building practice there are relatively few construction materials that are utilized, and a knowledge of transmission loss theory is most helpful in properly applying them. The most common materials are concrete, concrete masonry units (cmu), stucco, gypsum plaster, gypboard, and wood or metal sheets in various combinations. The structural supports are wood or metal studs for walls, and concrete, steel, or wood-joist systems for floors. At low frequencies providing adequate stiffness...

Figure 202 Balcony Design

Architectural Reflecters

Fair leading edge to reduce reflections balcony overhang is very deep, both direct and reverberant sound have difficulty penetrating. A sound system can augment the direct sound, using loudspeakers located on the underside of the balcony. A concave or semicircular-ceiling cavity under the balcony can help generate a localized reverberant field to offset the effect of a deep overhang. In rare instances, halls have been built with a flying balcony, separated from the rear wall of the room as in...

Vibration Isolators

Commercially available vibration isolators fall into several general categories resilient pads, neoprene mounts, and a combination of a steel spring and neoprene pad (Fig. 11.11). An isolator is listed by the manufacturer with a range of rated loads and a static deflection, which is the deflection under the maximum rated load. Most isolators will tolerate some loading beyond their rated capacity, often as much as 50 however, it is good practice to check the published load versus deflection...

Figure 2225 Elevation Cues from Pinna Reflections CIPIC 2001

Technique in theme park audio design where effects or dialog loudspeakers are located in props or set pieces constructed of perforated metal or other transondent materials. If there is more than one loudspeaker such as a central cluster with additional overhead loudspeakers, the earliest arrival time determines the perceived direction. Stereo loudspeakers are the most commonly encountered reproduction configuration. In stereo reproduction, a phantom image can be positioned between the...

Floor Squeak Shiners

Floor squeak is generated most often in wood construction by the rubbing of a joist or panel on a nail that is not completely embedded. Called shiners, these nails occur when framers use nail guns to secure the plywood diaphragms to the joists and miss their target. If the nail is not centered it will pass through the plywood and lay alongside the joist as in Fig. 12.27. When the floor deflects due to the passage of a walker, the joist moves and the nail rubs against the wood, creating a...

Table 169 Required Composite and Component FSTC for Various Voice Levels Chanaud 1983

Background Noise 44 dBA Minimum Composite FSTC for sound pressure level due to a normal voice in one room would generate about 18 dBA sound pressure level in the adjacent room. If the masking level in the receiving space were 35 dBA, we could achieve Confidential Privacy since the signal-to-noise ratio is less than -12 dB. This describes a typical private office with a background level of about NC 30 although the NC spectrum is not identical with the masking spectrum. The choice of an...

Beginnings Of Modern Acoustics

The nineteenth century produced the beginnings of the study of acoustics as a science and its dissemination in the published literature via technical books and journals. Heretofore scientific ideas had a relatively limited audience and were often distributed through personal correspondence between leading scholars of the day. Frequently written in Latin they were not generally accessible to the public. In the nineteenth century, books written in English or German, such as Hermann von Helmholtz...

Party Floorceiling Separations

Noise and vibration problems encountered in floor-ceiling systems fall into the four categories discussed in Chapt. 12 airborne noise, structural deflection, footfall, and floor squeak. Floor vibration and vibration isolation of mechanical equipment are separate topics, which were discussed in Chapt. 11. Airborne noise isolation in floors follows the same principles and is tested in the same manner as airborne isolation in walls. As was the case with wall transmission, the isolation of airborne...

Origins Of Sound Theory

The understanding of the theory of fluids including sound propagation through them made little progress from the Greeks to the Renaissance. Roman engineers did not have a strong theoretical basis for their work in hydraulics (Guillen, 1995). They knew that water flowed downhill and would rise to seek its own level. This knowledge, along with their extraordinary skills in structural engineering, was sufficient for them to construct the massive aqueduct systems including rudimentary siphons....

Figure 1625 Flanking around Walls at Mullions

Plasterboard Mullions Connect

When an interior wall meets the curtain wall at a mullian the connection can be made as shown. To block the Flanking path through the mullian an additional layer of drywall or 1 b & a sheet metal can be added to each side. When an interior wall meets the curtain wall between mullions the wall should be jogged to meet the mullian. When an interior wall meets the curtain wall between mullions the wall should be jogged to meet the mullian. This thickens the appearance of the mullion as seen...

Design Of Specific Room Types Small Auditoria

The acoustical design of an auditorium is more complicated than that of a lecture hall, however the general principles are very similar. The variety of seating layouts, wall shapes, and ceiling designs is much greater in theaters than in lecture halls. Figure 20.6 shows several theater-seating arrangements, including the traditional proscenium stage, an open stage, thrust stage, and an arena stage. Of these, the proscenium stage arrangement is the most serviceable. In a proscenium theater the...

Table 212 Background Noise Levels in Studios and Listening Rooms

Noise Level NC 25-30 NC 30-35 NC 25-30 NC 25-30 NC 20-25 NC 25-30 NC 20-25 NC 20-25 NC 15-20 NC 10-15 NC 10-15 < NC 10 terms of the NC level. A-weighted levels are about 5 dB higher for HVAC-generated noise. Although NC 10 is not formally defined, it is taken to be approximately 4 dB below NC 15 from 63 Hz to 500 Hz and 5 dB below NC 15 at 1000 Hz and above. Note that the higher background levels in music practice rooms are desirable due to the masking they provide. Low background-noise...

Floor Flan

Figure 21.21 Film Projector Noise at Two Feet Figure 21.21 Film Projector Noise at Two Feet at 24 and 30 frames per second. Noise isolation design is straightforward. For 35 mm 24 f s projectors the projection port can be double glazed 1 4 lam + 3 AS + 1 4 with at least one pane tilted away from vertical, not so much for sound isolation, but to prevent multiple reflected images on the screen. Laminated glass can be used in a projection port without degrading the image quality. Loudspeakers...

Concert Halls

Concert halls are rooms designed specifically for music in which the musicians and the audience occupy the same space. Classic concert halls are roughly rectangular and have one or more shallow balconies. In good concert halls the number of seats ranges from 1700 to 2600, with the best halls averaging around 1850. Above 2600 seats, the chances of success are much reduced and the preferred capacity is between 1750 and 2200. There is no division between the stage and the audience in a concert...

Loudness

Loudness is the human perception of the magnitude of a sound. Early efforts to quantify loudness were undertaken in the field of music. The terms very loud, loud, moderately loud, soft, and very soft were given symbols in musical notation ff, f, mf, p, and pp, after these words in Italian. But the terms are not sufficiently precise for scientific use, Figure 3.8 Relative Pitch Discrimination vs Frequency (Kinsler et al., 1982) Figure 3.8 Relative Pitch Discrimination vs Frequency (Kinsler et...

Water Hammer

Water hammer is a shock wave, usually generated by the rapid closure of a valve, but occasionally caused by a pressure wave resonance within a pipe. In the case of an isolated occurrence, it produces a violent slamming, which physically moves the pipe and causes a loud banging noise. In the case of a resonance the passage of a shock wave back and forth results in a very loud low-frequency buzzing sound. Water hammer creates a dramatic effect, which if allowed to continue, can result in damage...

Human Hearing Mechanisms Physiology of the

Physiology Hearing Diagrams

The human ear is an organ of marvelous sensitivity, complexity, and robustness. For a person with acute hearing, the range of audible sound spans ten octaves, from 20 Hz to 20,000 Hz. The wavelengths corresponding to these frequencies vary from 1.7 centimeters (5 8 inch) to 17 meters (57 feet), a ratio of one thousand. The quietest sound audible to the average human ear, about zero dB at 1000 Hz, corresponds to an acoustic pressure of 20 x 10-6 N m2 or Pa. Since atmospheric pressure is about...

Specialized Design Problems

Once the seating capacity and floor plan layout have been established, multipurpose auditoria still have a common set of specialized design problems to be solved. These include the shape and structure of the side walls and ceiling surfaces, the configuration of the orchestra shell and how it is stored, the layout of the pit and access to it, the accommodation of variable-acoustic elements including room volume, absorption and diffusion, and the inclusion of audio visual elements. Side wall and...

General Design Considerations

Different Shapes Bank Floor Plan

Although there are design features unique to the type of room, there are also general guidelines for large mixed-use facilities that apply to all of these rooms. 1. The source should be elevated above the seated audience so that sight lines are clear of obstruction. 2. A sound system capable of reproducing the full program frequency range must be incorporated into the design. The loudspeaker layout should be arranged so that the talker is the perceived origination point. 3. Where unamplified...

Motion Picture Theaters

Although motion pictures include speech and music, the design of movie theaters is driven by speech intelligibility considerations rather than by the need to provide reverberant support for unamplified music. The theater itself is an important link in the production chain since a film, as a mass-produced entertainment medium, is most effective if it is viewed in a controlled environment that yields the same auditory experience for every patron. Not all movie theaters are the same but they...

Q

Of the directivities of the individual sources and the directivity due to the array. Qe 9, 0 Q0 Qrel 9, 0 R2 9, 0 6.63 where Qe 9, 0 overall array directivity Q0 on - axis directivity for an individual speakers Qrel 9, 0 off - axis directivity of a given loudspeaker R2 9, 0 array directivity relative to the on - axis sound intensity If the array is composed of different types of loudspeakers or loudspeakers at various levels, for which there is no ready directional characteristic, the...

Table 192 Musical Terms and the Related Acoustical Factors

Reverberation time Early-to-late energy ratio Speed of the music Initial delay gap Proximity to the musicians Apparent source width of early sound Listener envelopment by the reverberant sound Frequency balance in reflection and absorption Lateral reflections Reverberant sound Musicians' ability to hear each other Level of the fortissimo minus the background noise level receiver's location determines the sound stage of his listening experience. In a rectangular room the listener is positioned...

Exterior To Interior Noise Transmission

As was the case for room to room transmission loss, exterior to interior noise transmission depends on the weakest link in the chain, which in most cases is either the windows or the doors. Where a site is located in a noisy area and a quiet interior noise environment is desired, windows and doors that have a high transmission loss values are critical. Unless exterior levels are quite high, standard California building practices, including stucco exterior walls on wood studs with R-11 3 1 2 or...

Speech Privacy In Closed Offices

In a closed office the assessment of privacy is expressed in terms of STC values between adjoining spaces. Closed offices have the advantage of providing privacy throughout the enclosed space for a standing or seated occupant. The disadvantage is that the normal background level is lower, even when masking is included, and conversations may take place at raised voice levels even when confidential matters are being discussed. Specialized areas such as psychologists' offices, spaces used for...

F

1000 1.9330 0.0000 0.0000 6.135E-2 2000 2.7300 0.0000 0.0000 -7.341E-2 4000 2.8000 0.0000 0.0000 -0.1467 8000 1.5450 0.0000 0.0000 -5.452E-2 Because of flanking paths, the duct attenuation in both round and rectangular ducts is limited to 40 dB. As with rectangular ducts, the unlined attenuation may be added to the lined attenuation. For circular ducts it is such a small contribution that it is usually ignored. It is frequently the case that the last duct run in a supply branch is made with a...

Control Of Duct Borne Noise

A typical duct borne noise transmission problem is illustrated in Fig. 14.14. A fan is located in a mechanical enclosure and transmits noise down a supply duct and into an occupied space. On the return side the ceiling space acts as a plenum for return air, which enters through a lined elbow. There could well be more paths to analyze, such as breakout from the side of a supply or return elbow before the silencer however, for purposes of this example, we limit it to these two. The starting point...

Gothic Period 11001400 Gothic Cathedrals

Beginning in the late middle ages, around 1100, there was a burst in the construction of very large churches, the Gothic cathedrals, first in northern France and later spreading throughout Europe. These massive structures served as focal points for worship and repositories for the religious relics that, following the return of the crusaders from the holy lands, became important centers of the valuable pilgrim trade. The cathedrals were by and large a product of the laity, who had developed from...